There are some challenges associated with planting corn on corn vs. corn following soybeans. These challenges include different fertility needs and higher residue levels. There are several steps you can take at planting to maximize yield potential on your corn on corn acres.
Seeding Depth. Corn will develop a better root system when planted 2 to 3 inches deep. Planting too shallow may inhibit formation of nodal roots and lead to rootless corn syndrome. At this depth you can expect more uniform temperatures and the seed will be protected from low nighttime temperatures. A uniform seeding depth translates to more uniform emergence.
Seeding Environment. Plant corn about 4 to 5 inches off from the previous year’s row. This will facilitate better depth control and improve seed-to-soil contact. Avoid planting directly in-between old rows. Planting in the center of old rows can make setting a planter for uniform seed placement more difficult as some rows will be planted in compacted areas (last year’s wheel tracks) and some rows will be planted into non-trafficked row middles.
Planting Speeds. Planting at high speeds impacts the uniformity of seeding depth and seed-to-soil contact. This can place seeds in different moisture and temperature conditions, resulting in less uniform emergence. To reduce planter unit bounce and increase uniformity of seed placement. Take the time to check planter seed placement in each field so you can adjust your speed or equipment as necessary.
Residue Management. Higher levels of residue can interfere with stand establishment by slowing the warming and drying of soil. Residue can also affect the furrow opening and closing functions of the planter’s row units. Consider using row-cleaning attachments on the planter to move surface debris.
If hair pinning residue is a problem, plant deeper. With a shallow planting, openers are pushing downward on the residue rather than cutting it. A 15-inch diameter disk opener cuts residue most efficiently when operated about 2 to 3 inches deep. Maintain sharp cutting edges on openers to quickly cut through residue.
Optimizing Fertility. Corn removes more soil phosphorus and less soil potassium per acre than soybean. A one-time switch to second-year corn will not greatly affect soil P and K levels, but if your fields have been planted to corn for multiple years you should monitor soil P and K levels and adjust fertilizer application rates as needed. Consider using a starter fertilizer containing N and P in a 2×2 placement. Research has shown a positive response to starter fertilizer when soil test P levels were below optimum.